U.S. patent number 4,846,164 [Application Number 07/083,690] was granted by the patent office on 1989-07-11 for vapor permeable dressing.
Invention is credited to Joel D. Martz.
United States Patent |
4,846,164 |
Martz |
July 11, 1989 |
Vapor permeable dressing
Abstract
A water vapor permeable dressing, such as a surgical dressing,
is constructed of a thin elastomeric transparent film which is
protected by a layer of non-woven fabric, preferably a fabric of
spun-bonded material. The fabric is sufficiently thin, elastic and
fluffy to absorb stress of abrasive objects so as to protect the
underlying film. Both the film and the protective fabric are
sufficiently thin and compliant to allow the dressing to conform to
the contours of the human body. Adhesive used in the dressing, for
securing the film to a person's skin, as well as for securing the
fabric to the film, are permeable to water vapor, The film and the
adhesives are impermeable to liquid water, thereby to provide an
effective shield for a wound against infection by outside
bacteria.
Inventors: |
Martz; Joel D. (Lawrence,
NY) |
Family
ID: |
22180039 |
Appl.
No.: |
07/083,690 |
Filed: |
August 7, 1987 |
Current U.S.
Class: |
602/58; 428/90;
604/304 |
Current CPC
Class: |
A61F
13/023 (20130101); A61L 15/26 (20130101); A61L
15/26 (20130101); C08L 75/04 (20130101); A61F
13/8405 (20130101); A61F 2013/00153 (20130101); A61F
2013/00182 (20130101); A61F 2013/00259 (20130101); A61F
2013/00919 (20130101); A61F 2013/15243 (20130101); A61F
2013/49042 (20130101); A61F 2013/51411 (20130101); A61F
2013/51447 (20130101); A61F 2013/530802 (20130101); A61F
2013/53445 (20130101); A61F 2013/53908 (20130101); A61F
2013/8479 (20130101); Y10T 428/23943 (20150401) |
Current International
Class: |
A61F
13/02 (20060101); A61L 15/16 (20060101); A61L
15/26 (20060101); A61F 13/15 (20060101); A61F
13/00 (20060101); A61L 015/00 () |
Field of
Search: |
;128/155,156,335
;604/304,307,358 ;428/89,90,97 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Yeung; James C.
Attorney, Agent or Firm: Warren; David M.
Claims
What is claimed is:
1. A moisture-vapor-permeable dressing for use on human and animal
skin comprising:
a conformable elastomeric film to be placed on the skin, the film
being permeable to water vapor but impermeable to liquid water;
an adhesive disposed as a breathable layer along a first surface of
said film for securing said film to the skin; and
a protective layer of conformable elastomeric fabric of nonwoven
filamentary material bonded to a second surface of said film
opposite said first surface to form therewith a composite laminated
structure, said protective layer of nonwoven material having a
discontinuous form open to a transpiration of water vapor at a rate
substantially greater than the permeability of said film, said
protective layer of nonwoven material having a multidimensional
recoverable elastic strain at least double an unstrained length of
the material so as to be conformable to a human or animal body; and
wherein
said protective layer deforms more readily, in response to an
abrasive force, than does a composite structure comprising said
film, said adhesive and the skin secured by the adhesive to said
film thereby to distribute an abrasive force over the composite
structure to inhibit tearing of said film.
2. A dressing according to claim 1 further comprising a release
sheet removably securable to said first surface of said film, for
detachment from said adhesive prior to application of said dressing
to the skin.
3. A dressing according to claim 1 further comprising a second
layer of a breathable adhesive, said protective layer being bonded
to said second surface of said film by said second layer of
adhesive.
4. A dressing according to claim 1 wherein said film is transparent
and a portion of said protective layer is cut away to form a window
for viewing skin beneath said film.
5. A dressing according to claim 4 further comprising a section of
protective layer material adhesively securable about said window as
a window shade for occluding a view of skin beneath the window.
6. A dressing according to claim 1 wherein said protective layer is
fused to the second surface of said film.
7. A dressing according to claim 1 further comprising absorptive
pad means secured to said film at a portion of said first surface
for absorbing exudate from the skin.
8. A dressing according to claim 1 wherein said protective layer
extends beyond a perimeter of said film.
9. A dressing according to claim 8 further comprising absorptive
pad means secured to said film at a central portion of said first
surface for absorbing exudate from the skin.
10. a dressing according to claim 1 wherein said nonwoven material
is spun-bonded.
11. A dressing according to claim 1 wherein said nonwoven material
is spun-bonded urethane.
12. A dressing according to claim 1 wherein said nonwoven material
is a perforated sheet of plastic material.
13. A dressing according to claim 1 wherein a periphery of said
nonwoven material is formed in the shape of a cartoon-type of
image.
14. A dressing according to claim 1 wherein the nonwoven material
is imprinted with a cartoon-type of image.
15. A dressing according to claim 14 wherein a periphery of said
nonwoven material is formed in the shape of a cartoon-type of
image.
16. A dressing according to claim 15 further comprising:
an additional layer of nonwoven material placed over a portion of
an outer surface of the dressing to form a pocket; and
a miniaturized music device held within said pocket.
17. A dressing according to claim 1 further comprising an
additional layer of nonwoven material placed over a portion of an
outer surface of the dressing to form a pocket, said pocket being
suitable for holding a sound-producing device.
18. A dressing according to claim 1 wherein a part of said film
extends beyond an edge of said nonwoven material to form a tab.
19. A dressing according to claim 1 wherein said nonwoven material
extends beyond a periphery of said film to form a border enclosing
said film.
20. A moisture-vapor-permeable dressing for use on human and animal
skin comprising:
a conformable elastomeric film to be placed on the skin, the film
being permeable to water vapor but impermeable to liquid water;
a breathable adhesive disposed as a layer along a first surface of
said film for securing said film to the skin, said film with said
adhesive together having a moisture-vapor-permeability greater than
approximately 250 grams per square meter per 24 hour interval of
time at a relative humidity of 80%; and
a protective layer of conformable elastomeric fabric of nonwoven
material bonded to a second surface of said film opposite said
first surface to form therewith a composite laminated structure,
said protective layer of nonwoven material having a discontinuous
form open to a transpiration of water vapor at a rate substantially
greater than the permeability of said film to provide said
laminated structure with a rate of water vapor transpiration
essentially the same as that of said film with said adhesive; and
wherein
said protective layer deforms more readily, in response to an
abrasive force, than does a composite structure comprising said
film, said adhesive and the skin secured by the adhesive to said
film, thereby to distribute an abrasive force over the composite
structure to inhibit tearing of said film; and
further comprising a second layer of a breathable adhesive, said
protective layer being bonded to said second surface of said film
by said second layer of adhesive; and
wherein said second layer of adhesive is disposed on a surface of
said protective layer, there being a release coat on the second
surface of said film for releasing at least a part of said
protective layer from said film without disconnection of said film
from the skin, said film being transparent to permit a viewing of
skin beneath said dressing.
21. A moisture-vapor-permeable dressing for use on human and animal
skin comprising:
a conformable elastomeric film to be placed on the skin, the film
being permeable to water vapor but impermeable to liquid water;
a breathable adhesive disposed as a layer along a first surface of
said film for securing said film to the skin, said film with said
adhesive together having a moisture-vapor-permeability greater than
approximately 250 grams per square meter per 24 hour interval of
time at a relative humidity of 80%; and
a protective layer of conformable elastomeric fabric of nonwoven
material bonded to a second surface of said film opposite said
first surface to form therewith a composite laminated structure
said protective layer of nonwoven material having a discontinuous
form open to a transpiration of water vapor at a rate substantially
greater than the permeability of said film to provide said
laminated structure with a rate of water vapor transpiration
essentially the same as that of said film with said adhesive; and
wherein
said protective layer deforms more readily, in response to an
abrasive force, than does a composite structure comprising said
film, said adhesive and the skin secured by the adhesive to said
film, thereby to distribute an abrasive force over the composite
structure to inhibit tearing of said film; and
wherein said second layer of adhesive is disposed on a surface of
said protective layer, there being a release coat on the second
surface of said film for releasing at least a part of said
protective layer from said film without disconnection of said film
from the skin, said film being transparent to permit a viewing of
skin beneath said dressing;
a portion of said protective layer is cut away to form a window for
viewing skin beneath said film; and
said dressing further comprises a second of protective layer of
material adhesively securable about said window as a window shade
for occluding a view of skin beneath the window.
22. An elastic bandage formed of a strip of nonwoven filamentary
material, said nonwoven material being a spun-bonded elastomer,
said nonwoven material having a multidimensional recoverable
elastic strain at least double an unstrained length of the nonwoven
material to be conformable to a patient's body, there being a
flocking of water-absorbent material secured to a surface of the
nonwoven material.
23. An elastic bandage according to claim 22 wherein said material
is imprinted with a design which extends upon a stretching of the
bandage during application of the bandage to a limb of a person,
the appearance of the design being indicative of a desirable amount
of stretching.
24. A moisture-vapor-permeable dressing for use on human and animal
skin comprising:
a conformable elastomeric film to be placed on the skin, the film
being permeable to water vapor but impermeable to liquid water;
a breathable adhesive disposed as a layer along a first surface of
said film for securing said film to the skin, said film with said
adhesive together having a moisture-vapor-permeability greater than
approximately 250 grams per square meter per 24 hour interval of
time at a relative humidity of 80%; and
a protective layer of conformable elastomeric fabric of nonwoven
material bonded to a second surface of said film opposite said
first surface to form therewith a composite laminated structure,
said protective layer of nonwoven material having a discontinuous
form open to a transpiration of water vapor at a rate substantially
greater than the permeability of said film to provide said
laminated structure with a rate of water vapor transpiration
essentially the same as that of said film with said adhesive; and
wherein
said protective layer deforms more readily, in response to an
abrasive force, than does a composite structure comprising said
film, said adhesive and the skin secured by the adhesive to said
film, thereby to distribute an abrasive force over the composite
structure to inhibit tearing of said film; and
said dressing further comprises an additional layer of nonwoven
material placed over a portion of an outer surface of the dressing
to form a pocket, there being means within said pocket for
dispensing a liquid medicine via said permeable film to be absorbed
by said skin.
25. A surgical dressing comprising:
a conformable elastomeric film permeable to water vapor but
impermeable to liquid water;
a protective layer of conformable elastomeric fabric bonded to said
film to form therewith a laminated structure, said protective layer
of fabric having a multidimensional recoverable elastic strain at
least double an unstrained length of the fabric to be conformable
to a patient's body; and
adhesive means disposed along said film on a side opposite said
protective layer for securing said dressing to the flesh of a
patient, and wherein said laminated structure together with said
adhesive means are permeable to water vapor, said laminated
structure being sufficiently elastic to conform to contours of the
patient's flesh; and wherein
said protective layer is opaque, the bonding of said protective
layer to said film providing for a releasable securing of said
protective layer to said film to permit a viewing of the flesh.
26. A dressing according to claim 25 having a construction in the
form of a cartoon character.
27. A surgical dressing comprising:
a conformable elastomeric film permeable to water vapor but
impermeable to liquid water;
a protective layer of conformable elastomeric fabric bonded to said
film to form therewith a laminated structure, said protective layer
of fabric having a multidimensional recoverable elastic strain at
least double an unstrained length of the fabric to be conformable
to a patient's body; and
adhesive means disposed along said film on a side opposite said
protective layer for securing said dressing to the flesh of a
patient, and wherein said laminated structure together with said
adhesive means are permeable to water vapor, said laminated
structure being sufficiently elastic to conform to contours of the
patient's flesh; and wherein
said protective layer deforms more readily in response to an
abrasive force than does a composite structure comprising said
film, said adhesive and the skin secured by the adhesive to said
film, thereby to distribute an abrasive force over the composite
structure to inhibit tearing of said film.
28. A dressing according to claim 27 having a construction in the
form of a cartoon character.
29. A breathable surgical dressing comprising:
a conformable elastomeric film permeable to water vapor but
impermeable to liquid water;
a protective layer of conformable elastomeric fabric bonded to said
film to form therewith a laminated structure; and
adhesive means disposed along said film on a side opposite said
protective layer for securing said dressing to the flesh of a
patient, said laminated structure being sufficiently elastic to
conform to the contours of the patient's body; and wherein
the bonding of said protective layer to said film provides for a
releasable securing of said protective layer to said film to permit
a viewing of the flesh, said fabric comprising filaments of
elastomeric material arranged to form openings for transpiration of
water vapor, the fabric having a density in the range of
approximately 15-250 grams per square meter and a thickness in the
range of approximately 0.05-0.75 millimeters.
30. A breathable surgical dressing comprising:
a conformable elastomeric film permeable to water vapor but
impermeable to liquid water;
a protective layer of conformable elastomeric fabric bonded to said
film to form therewith a laminated structure, said protective layer
of fabric having a multidimensional recoverable elastic strain at
least double an unstrained length of the fabric to the conformable
to a patient's body; and
adhesive means disposed along said film on a side opposite said
protective layer for securing said dressing to the flesh of a
patient, said laminated structure being sufficiently elastic to
conform to the contours of the patient's body; and wherein
said protective layer deforms more readily in response to an
abrasive force than does a composite structure comprising said
film, said adhesive and the skin secured by the adhesive to said
film, thereby to distribute an abrasive force over the composite
structure to inhibit tearing of said film, said fabric comprising
filaments of elastomeric material arranged to form openings for
transpiration of water vapor, the fabric having a density in the
range of approximately 15-250 grams per square meter and a
thickness in the range of approximately 0.05-0.75 millimeters.
Description
BACKGROUND OF THE INVENTION
This invention relates to moisture vapor permeable film dressings
for covering wounds on human and animal skin, and, more
particularly, to a structure of a thin transparent moisture vapor
permeable film dressing with a moisture vapor permeable adhesive,
there being a vapor permeable non-woven fabric secured to the film
on a side opposite the adhesive to facilitate manipulation of the
dressing, and to provide the thin film with protection from
abrasion. The dressing may include optionally a pad on the adhesive
side of the film for adsorption of body exudate. The composite
structure of the film and the nonwoven fabric is sufficiently thin
and elastic to readily conform to the shape of a body being draped
by the dressing.
The use of thin films on the order of one mil thickness, which are
impermeable to liquid water but permeable to water vapor is finding
increased use in the construction of surgical dressings. Such
dressings may include the film with or without a gauze pad or other
absorptive plus some form of backing layer to facilitate
emplacement of the dressing on the wound. Occasionally, the
dressing is completed by use of gauze or other fabric which covers
the film so as to protect the fragile film from abrasion and/or
puncture by foreign objects which may contact the patient wearing
the dressing.
The use of the thin film is advantageous for a number of reasons.
The film is impermeable to liquid water and to bacteria so as to
form a very effective shield which protects a patient from sources
of infection external to the skin. The film retains body fluids
within the body at the site of the wound. The vapor permeability of
the film provides a sufficient rate of water vapor transport
through the film to allow the skin to breathe normally. The film
has sufficient elasticity to conform to the shape of various parts
of the body, even a flexible body part such as a knee or elbow.
Both the film and the adhesive layer may be constructed to be
transparent, such transparency permitting the physician to observe
the wound area without removal of the dressing. The material of the
dressing is non-allergenic. The foregoing characteristics of the
dressing permit the dressing to be kept in place for significantly
longer periods of time than with other non-film types of dressings,
this resulting in a great convenience to both the patient and
attending medical staff, and also providing for better healing in
some types of breaks in the integument, incisions, or wounds and
providing better cost effectiveness in medical practice due to
decreased need for dressing changes.
Such moisture vapor permeable films may be made from synthetic
polymers and formed by casting, extrusion or other known
film-making processes. Film thickness is in a range of typically
0.5-10 mils and preferably in a range from 0.6-3 mils. The film is
continuous in that it has no perforations or pores which extend
through the depth of the film. Films of this type are known and
generally are hydrophyllic polymeric materials through which water
vapor is capable of diffusing. The films are formed of plastic
material such as polyurethane or acrylate copolymers, see McCracken
et al, U.S. Pat. No. 4,413,621. A suitable adhesive for securing
the thin film to human skin is disclosed in Hodgson, U.S. Pat. No.
3,645,835 (now U.S. Pat. Nos. Re. 31,886 and 31,887). Generally,
these films have moisture vapor transport rates between 15 and 80
grams per 100 square inches per 24 hour interval at 100.degree.
Fahrenheit and 90% Relative Humidity.
In spite of the many advantages of the thin film, there are
problems associated with its use. The film is too thin to be
handled without some form of backing sheet or release sheet because
the extreme flexibility and limpness allow the film to curl over
upon itself. Furthermore, in the presence of an adhesive layer on
one surface of the film, the film may stick to itself, this
presenting great difficulty in applying the film to a patient.
While the feature of transparency is most beneficial in allowing a
physician to observe the wound, this feature is distressing to a
patient who would prefer not to look at an ugly wound. The film,
because of its extreme thiness, is fragile, and can readily catch
on a sharp or rough object resulting in a tearing of a dressing
constructed of the film.
If an attempt be made to overcome the foregoing difficulties by use
of a permanent backing layer of greater stiffness and resistance to
abrasion, then a further problem is introduced, namely, such
backing layer would materially alter the vapor transport rate of
the dressing and might not allow any vapor transport. If an opaque
covering, such as a cloth bandage, be placed over the film to
occlude the distressing view of the wound from the patient, then
the disadvantage is introduced in that an attending physician must
remove the cloth covering in order to view the wound.
SUMMARY OF THE INVENTION
The aforementioned problems are overcome and other advantages are
provided by a thin dressing which, in accordance with the
invention, is fabricated of a thin film of polyurethane or other
similar elastomeric polymer or copolymer having an adhesive layer
on one surface and a nonwoven fabric secured to the opposite
surface. The composite structure of adhesive layer, film and
nonwoven fabric is permeable to water vapor and has a sufficiently
high transport rate of the vapor to permit the skin of a patient
receiving the dressing to aspirate water vapor normally through the
dressing. The film and the adhesive layer are transparent. The
nonwoven fabric is opaque, and is constructed as a spun-bonded
elastic material. Alternatively, the nonwoven fabric may also be
constructed as a highly perforated elastic film of material similar
to the foregoing thin film, the large amount of perforation
permitting the transport of water vapor without adding any
significant resistance to the vapor flow. The nonwoven elastic
fabric has an extensive amount of voids passing completely through
the fabric which allows passage of both liquid water and water
vapor. However, the thin film is impervious the the liquid water so
that the presence of spun-bonded material n no way reduces the
protective barrier of the thin film to infection. The nonwoven
fabric has recoverable elastic strain at least double the
unstrained length, the elasticity and recoverability being
multidimensional so as to be conformable to body contours and
provides unhindered full range of motion on joints of a patient
wearing the dressing.
It is an object of the invention to facilitate use of the dressing
by an attending physician. It is a further object of the invention
to reduce distress and introduce a measure of comfort to a patient
wearing the dressing.
Use by an attending physician is facilitated by virtue of an
inherent stiffness to the nonwoven fabric, which stiffness
overcomes the tendency of the thin film to curl upon itself, the
nonwoven fabric enabling the physician to readily manipulate the
dressing for emplacement upon a wound. An elastic nonwoven fabric
stretches along with the elastic film during positioning on the
patient. A release sheet covers the adhesive layer until
emplacement of the dressing upon the wound, at which time the
release sheet is removed to expose the adhesive layer to the
patient's skin. If desired, a gauze pad, foam or other absorptive
device may be included within the dressing, the absorptive pad
being positioned on the adhesive side of the film. The foregoing
multiple laminate structure of the dressing is readily packaged,
dispensed, and manipulated in a hospital situation.
The nonwoven fabric is bonded to the film by a fusing or by use of
an adhesive. Such bonding retains the vapor transport
characteristic of the dressing. The dressing may be constructed in
a manner which allows the physician to view the wound without
removal of the dressing. This is accomplished in one embodiment of
the invention by the construction of a window in the fabric, and by
adhesively securing a further layer of fabric over the window to
act as a shade for opening and closing the window, thereby to show
or hide the wound. Alternatively, the surface of the film facing
the fabric may be provided with a release coat permitting an
adhesively secured fabric to be retracted away from the film for
viewing the wound, after which the fabric is restored to its
original position upon the film. In the window-shade construction,
a release coat may be placed on the outer surface of the fabric to
facilitate lifting and replacement of the window shade.
In the use of the dressing on young children, children can be
comforted in the distressing situation of a bodily wound by
imprinting a colored likeness of a cartoon, animal, or other
character upon the fabric. The shape of the final dressing may
follow the contour of the imprint.
It is also noted that the nonwoven elastic fabric itself, due to
its elasticity, its elastic recoverability, and its capacity for
allowing skin to breathe, can be used as an elastic bandage, as for
binding a sprained joint. The fabric can be much thinner than
currently employed woven or knitted fabrics for this purpose and
still retain adequate strength for use in binding sprained joints.
This is particularly advantageous in the case of a binding of a
sprained ankle because the fabric is thin enough to be worn within
a shoe.
The elastic properties of the nonwoven material can also be
employed for fabricating an elastic bandage. Since the nonwoven
material is in the nature of a plastic such as polyurethane which,
while being transmissive to sweat does not absorb sweat, increased
comfort to a wearer of the bandage is attained by flocking the
nonwoven material with particles of a material such as cotton or
rayon which absorbs sweat. The permeability of the nonwoven
material to moisture absorbed by the cotton or rayon prevents
excessive buildup of moisture in the flocking so as to maintain the
comfortably dry feeling to the wearer.
BRIEF DESCRIPTION OF THE DRAWING
The aforementioned aspects and other features of the invention are
explained in the following description, taken in connection with
the accompanying drawing wherein:
FIG. 1 shows a stylized view of a portion of a person's arm having
a dressing thereon, the dressing being constructed in accordance
with the invention;
FIG. 2 shows a cross-sectional view of the dressing taken along the
line 2--2 in FIG. 1;
FIG. 3 shows a plan view of an embodiment of the dressing wherein
nonwoven fabric extends beyond the perimeter of the film;
FIG. 4 shows an embodiment of the invention wherein a part of the
film protrudes as a tab from underneath the nonwoven fabric;
FIG. 5 shows a dressing in the form of a bandage with a cartoon
sketched thereon, the cartoon showing a face wherein a mouth is
placed at a point of flexture on a knee of a patient's leg to show
an opening of the mouth when the leg is flexed, and wherein
nonwoven fabric extends beyond the perimeter of the film;
FIG. 6 shows a dressing formed as bandage which can be dispensed by
a child, a periphery of the nonwoven fabric extending beyond the
periphery of the film and being shaped in the form of a cartoon
wherein nonwoven fabric extends beyond the perimeter of the
film;
FIG. 7 is an enlarged fragmentary sectional view showing an edge of
the dressing in an embodiment wherein the nonwoven fabric is fused
to the film;
FIG. 8 shows the view of FIG. 7 under conditions wherein the
nonwoven fabric is being abraided by a pointed object such as a
hairpin, FIG. 8 including a diagrammatic representation of lines of
stress to demonstrate the distribution of stress about a large
surface region of the film;
FIG. 9 is an enlarged fragmentary view of a dressing employing a
multiply perforated plastic sheet as the nonwoven fabric;
FIG. 10 shows a construction of an electrode suitable for adhesion
to a human body for measurement of body functions, the electrode
being formed of electrolyte absorbing material in combination with
a layer of nonwoven material; and
FIG. 11 shows a sectional view of a bandage structure in which
nonwoven fabric secures a gauze pad to skin.
DETAILED DESCRIPTION
With reference to FIGS. 1 and 2, a dressing 20 is applied to an arm
22 of a patient. The dressing 20 is constructed in accordance with
the invention, and includes a film 24 having a first adhesive layer
26 for securing the dressing 20 to skin 28 of the patient. The
dressing 20 is provided with a release sheet 30 such as siliconized
paper which covers the adhesive layer 26 prior to use of the
dressing 20. The release sheet 30 is shown partially removed in
FIG. 2, such removal being accomplished to expose the adhesive
layer 26 during emplacement of the dressing 20 upon the patient's
arm 22.
The dressing 20 further comprises a layer 32 of fabric which, in a
preferred embodiment of the invention, is formed of a sheet of
nonwoven elastic material such as a spun-bonded material or a
multiply perforated sheet of plastic. The fabric layer 32 is bonded
to a second surface of the film 24 opposite the first adhesive
layer 26 by fusing or, as shown in FIG. 2, by a second layer 34 of
adhesive. The second surface of the film may be provided with a
release coat 36 which cooperates with the second adhesive layer 34
to facilitate partial or complete removal of the fabric to enable a
physician attending the patient to view the portion of the skin 28
covered by the dressing 20. After such viewing, the fabric is
returned to its position on the film 24 and held in that position
by the second adhesive layer 34.
The dressing 20, as described so far, constitutes a first
embodiment of the invention which is capable of protecting an area
of the skin from infection, and which permits a viewing of the
region of the skin beneath the dressing 20 by releasably securing
the fabric to the film 24 by an attending physician. The fabric
layer 32 is opaque so as to hide the wound, skin and any
discoloration or exudate which may be produced by the patient.
By way of further embodiment of the dressing 20, a window 38 can be
formed within the fabric layer 32 by cutting away a portion of the
fabric layer 32 having the desired shape, typically round or
square, of the window 38. The window 38 permits a viewing of the
skin without removal of the layer of fabric layer 32. In order to
protect the portion of the film 24 bounded by the window 38, and to
close off the window 38 from a viewing by the patient, a window
shade 40 is removeably secured about the window 38. The shade 40
comprises a flap 42 of the fabric and a third adhesive layer 44
which secures the shade 40 to the top surface of the fabric layer
32. The top surface of the fabric layer 32 may be provided with a
release coat 46 to facilitate removal of the shade 40, and to
permit the shade 40 to be replaced and secured by the adhesive
layer 44 to the fabric layer 32.
By way of further embodiment, a gauze pad 48 of cotton or other
absorbent material may be secured to the first side of the film 24
for absorbing exudate from a wound 50 in the skin 28. The window 38
permits a viewing of the pad 48 so as to determine how much oozing
of body fluids may have occurred at the site of the wound 50.
FIGS. 3 and 4 show further configurations of the dressing 20. In
FIG. 3, the fabric 32 extends beyond the periphery of the film 24
to provide a border 52 which completely surrounds the film 24. This
configuration is useful as a bandage which can be applied by a
child to cover a wound. In the dressing 20 of FIG. 4, the film 24
is provided with a tab 54 which extends beyond an edge of the
fabric 32. This facilitates a separation of the fabric 32 from the
film 24 when it is desired to lift a portion of the fabric 32 for
viewing the wound 50 or gauze pad 48.
With reference to FIG. 5, a feature of the invention is
demonstrated by placing the dressing on a knee 56 of the patient.
Therein, the fabric 20 is provided with a cartoon character printed
directly on the surface of the fabric 32. Such a character is an
aid to cheering children who may have undergone a surgical
procedure and, by reducing mental stress associated with the
recovery process, aids a return to good health. A particular
feature of the cartoon embodiment of the dressing 20 is the
emplacement of a mouth of the cartoon face at a point of flexure of
the knee 56 so that, upon a bending of the knee 56, the mouth is
stretched so as to appear to open. When the knee is brought to a
straight position, the mouth appears to close. This is a useful
feature, particularly in the case of young children, for enabling
some measure of happiness to be introduced into their lives.
If desired, a pocket 58 can be created on the front surface of the
fabric 32 by use of an additional layer of the fabric which is
adhesively secured at edges thereof to the layer of fabric 32. A
miniaturized music or sound-producing device 60 in the form of a
button is placed within the pocket 58. Alternatively, in lieu of
the music device 60, a sponge (not shown) of similar button shape
may be placed within the pocket 58, the sponge, or other pad of
liquid absorbent material, being saturated with a gel of a medicine
which can be administered by contact with the skin of a patient.
Liquid containing the medicine slowly passes from the sponge via
the moisture permeable dressing 20 to the skin of the patient. If
desired, the rate of passage of the medicine can be increased by
cutting away a portion of the dressing 20 within the pocket 58. The
dressing with the sponge-like material in the pocket 58 may be
regarded as a trans-dermal medication patch useful for the slow
administration of a drug such as nitroglycerin.
in FIG. 6, the cartoon aspect of the dressing 20 is embellished
still further by extending the fabric of the layer 32 well beyond
the perimeter of the film 24, and but cutting the outer edge of the
fabric to have the physical shape of a cartoon character. As used
herein and in the claims, the term "cartoon" is not limited to only
the facial configuration, but is intended to include shapes of
other objects frequently found in children's literature, such as,
rainbows, bells, and stars. Such a form 62 having an animal face
and long ears is shown in FIG. 6. In addition, an outline of facial
features is imprinted on the surface of the fabric to add further
realism to the cartoon form 62.
FIGS. 7 and 8 show an enlarged fragmentary view of an edge of a
dressing 20 in accordance with the first embodiment of the
invention comprising only the film 24 and the fabric 32 which
serves as a protective layer for the film 24. In the structure
disclosed in FIGS. 7 and 8, the fabric layer 32 is bonded to the
film 24 by fusing, a region 64 of the fusing being indicated in
FIG. 7.
FIG. 9 shows a construction of a dressing 70 having a fabric 72
formed of a sheet 74 of plastic having numerous apertures 76
extending through the sheet 74. the sheet 74 is elastomeric and,
with the apertures 76, has physical characteristics similar to
those of the fabric 32 of the dressing 20 in FIG. 2. In FIG. 9, the
fabric 72 is bonded to the film 24 in the same fashion as has been
described above for the bonding of the fabric 32 to the film 24.
There follows an analysis of the dressing 20 which is understood to
apply also to the dressing 70.
It is noted that the nonwoven material of the fabric layer 32 has
sufficient elasticity to permit abrasion by a pointed object, such
as a hair pin 66, as shown in FIG. 8. The fabric layer 32 distorts
under stress of the hair pin 66 while distributing stress lines 68
about a region of the film 24 which is substantially larger than
the region of contact of the hair pin 66 with the fabric layer 32.
In the preferred construction of the dressing 20, the nonwoven
material of the fabric layer 32 is spun-bonded. Spun-bonded
material has a substantially larger capacity to absorb deformation
from an abraiding object than does the film 24. Thus, an abraiding
object which might will tear the film 24 is kept away from the film
24 by the fabric layer 32. Thereby, the film 24 is protected by the
fabric so as to maintain integrity of the barrier against infection
from bacteria. It is further noted that the distribution of the
stress lines 68 about the relatively large area of the film 24
allows the film 24 to serve as a strong base for support of the
fabric layer 32 in resisting the force of abrasion without any
danger of tearing the film 24.
The film 24 may be of the form described hereinabove, which form is
constructed of a water vapor permeable polyurethane or acrylate
copolymer, or urethane and urethane copolymers as well as modified
polypropylene, which film is transparent and has sufficient
elasticity to be conformable to contours of a human body as well as
an animal body. Typically, the film 24 has a thickness in a range
of approximately 1-3 mils, though film thicknesses in the order of
0.5-10 mils may be considered. The thickness of the film in
combination with the amount of voids in the plastic material of the
film determine a transport rate for water vapor through the film. A
transport rate greater than approximately 250 grams per square
meter per 24 hour interval at a relative humidity of 80% is desired
in order to insure that the skin of a patient wearing the dressing
20 can breathe properly in the sense that the water vapor
discharged through the skin can permeate through the film 24 to be
evaporated in air. Further details in the construction of a
moisture vapor transmitting elastomeric film is disclosed in
Metcalfe et al, U.S. Pat. No. 4,596,738 issued June 24, 1986.
Further details in the construction of a moisture-vapor-permeable
pressure-sensitive adhesive material is disclosed in Hodgson, U.S.
Pat. No. 3,645,835 issued Feb. 29, 1972 and reissued as U.S. Pat.
No. Re. 31,886, on May 14, 1985.
The nonwoven material of the fabric 32 is particularly advantageous
over woven material because the nonwoven material can be
constructed in a form which is exceedingly thin for a protective
layer, typical thicknesses of the fabric layer 32 being in the
range of approximately 1-30 mils, with a typical value being
approximately 10 mils. The nature of the spun-bonding construction
introduces a low density to the spun-bonded material, much lower
than a solid form of the material, such that there are adequate
voids to allow for the evaporation of water vapor from the surface
of the film 24. In addition, such material has a relatively soft
fluffy feel which, in combination with the great elasticity,
provides for the above-noted capacity to absorb stress of an
abraiding object, thereby to provide for the protection of the film
24.
It is noted that spun-bonded material is employed in the practice
of the invention while woven fabric is not employed. This is
because available woven fabric does not have the combination of
thinness, elasticity, and air permeability of the spun-bonded
material. Should these characteristics become available in woven
fabric in the future, then such woven fabric may be employed in the
practice of the invention as an alternate component to the
spun-bonded material.
An alternative form of the fabric layer 32 employes a sheet of
plastic having multiple perforations in a range of typically 25-50
mils, and wherein the combined area of the apertures is in the
range of 5-30%, typically 17%, of the area of the plastic sheet.
This is a highly discontinuous fabric providing ample opportunity
for transpiration of water vapor. It is noted that the fabric is
not waterproof in the sense that liquid water can pass through the
fabric. However, the waterproof characteristic is not required of
the fabric layer 32 because the film 24 provides an adequate
barrier to the flow of water.
The spun-bonded material is formed by a fusing or by a chemical
interaction of filaments of material in a random pattern rather
than by weaving or knitting strands of material, as in knitted
fabric. By way of example, spun-bonded urethane is a thermal
plastic polyurethane elastomer formed as a spun-bonded fabric. The
fabric has a structure of three dimensional entanglement of
polyurethane fine continuous or discontinuous elastic filaments
which are thermally or chemically melt bonded. The fabric is
characterized by being stretchable in all directions, typically in
excess of two times the relaxed length. The fabric is highly
permeable to air because of the thinness of the fine filament
structure, the filaments of the structure being randomly webbed and
bonded only at their intersections to define interstices. The
thickness of the fabric is in a range of typically 0.05-0.75
millimeters. The density of the fabric is in a range of typically
15-250 grams per square meter.
The second and the third adhesive layers 34 and 44 are
solvent-based acrylic aerated adhesive layer having a thickness on
the order of one mil. Permeability to water vapor may be increased
by flash heating to sputter out the solvent vehicle which carries
the adhesive particles, the sputtering leaving voids in the
adhesive which facilitate transport of water vapor through a layer
of the adhesive.
The release coat, applied to the upper surface of the film 24, and
the release coat applied to the upper surface of the fabric layer
32 are formed, preferably, as a silicone-based coating. If desired,
the coating may be fused to the underlying substrate of film 24 or
layer 32 by heat. Such release coats may be cured by bombardment
with an electron beam or by treatment with an ultraviolet beam.
In a further aspect of the invention, it has been found that the
fabric layer 32, by itself, has sufficient tensile strength to be
used as an elastic bandage for binding wounds, such as a sprained
ankle, or other sprained joint. A spun-bonded material, such as a
polyurethane spun-bonded material, is transmissive to sweat without
absorbing the sweat. Increased comfort to a person wearing the
elastic bandage is attained by providing material which absorbs the
sweat. This is accomplished, in accordance with another aspect of
the invention by applying a sweat-absorbent material such as cotton
or rayon particles by a flocking of the particles on the
spun-bonded material. The flocking process comprises a spraying of
both an adhesive and the particles of cotton or rayon on the
spun-bonded material, the adhesive securing the flocked particles
on the spun-bonded material. Sufficient comfort is provided to the
wearer of the bandage by flocking only the side of the bandage
which faces the skin of the wearer. Also, if desired, the cartoon
characters can be imprinted on the material of the elastic bandage.
Also, the printing of other indicia on the elastic bandage can be
accomplished in a compressed format such that, upon a stretching of
the bandage during a binding of a wound, the indicia expand to the
desired proportions to indicate a proper amount of tension in the
elastic bandage.
The use of nonwoven material is, furthermore, distinctly
advantageous over the use of woven material because the nonwoven
material can be constructed as a much thinner sheet which allows
flexing of the film 24 without introduction of unnecessary stress
as might occur when a thin film of material is bent around a thick
layer of material, as would occur if woven material were used as
the protective layer. By use of two very thin layers, each having a
thickness on the order of one mil as is the case with the disclosed
film 24 and fabric layer 32, the resultant dressing has the
flexibility and conformability of the layer of skin which is
covered by the dressing 20. By considering this conformability
characteristic in combination with the capability to breathe, to
resist liquid water, and to exclude infectious agents, the dressing
20 may well be regarded as a synthetic skin. It is also noted that,
in view of the secure adhesive bond between the film 24 and the
skin 28 of the patient, the film and skin can be regarded as a
composite structure which serves as a foundation for support of the
protective layer 32 of fabric. This is an important part of the
protective mechanism which, as noted above with reference to FIG.
8, provides that the protective layer deforms more readily in
response to an abrasive force than does the composite structure of
the film and the skin. There results the distribution of the
abrasive forces about the composite structure of the film and skin
to reduce the magnitude of such force at any one point on the film,
thereby to inhibit a tearing of the film. In this respect, the
dressing 20 has a further characteristic of skin in that the fabric
32 may be likened to the epidermis which protects the dermis from
abrasive forces.
FIG. 10 shows the construction of a flexible electrode assembly 78
which is secured adhesively to the skin 80 of a patient, the
electrode assembly 78 being formed of a layer 82 of nonwoven fabric
such as the layer 32 of FIG. 2 so as to be moisture permeable and
comfortable for wearing by the patient. A flexible sponge 84 or
similar liquid absorbent material is enclosed by a flexible
elastomeric cap 86 which is fused to the layer 82 for securely
holding the sponge 84 in place. The cap 86 may be formed of the
same material as the layer 82. An aperture 88 is disposed within
the layer 82, and centered beneath the sponge 84. An electrode wire
90 passes through the cap 86 to make contact with the sponge 84,
the wire 90 being secured to the cap 86 by fusing of the cap
material about the wire 90.
In operation, the sponge 84 contains a gel of electrolyte which
provides an electrically conductive path between the wire 90 to the
skin 80, the electrolyte making contact with the skin 80 via the
aperture 88. The elastomeric properties of the nonwoven material of
the layer 82 and of the cap 86, wherein recoverable stretch may be
as much as 100% in three dimensions allows the electrode assembly
78 to conform to undulations in the skin 80 and to distend with
movement of the patient. This permits a much more secure holding of
the electrode assembly 78 to the skin 80 of the patient. In
addition, the moisture-permeable and air-breathable qualities of
nonwoven fabric, particularly spun-bonded fabric, in combination
with the extreme thinness of the fabric insure comfort in the
wearing of the electrode 78. The wire 90 is readily connected to
electronic measurement circuitry for use in patient monitoring
situations such as an electrocardiogram, transcutaneous nerve
stimulation, and an electromylogram.
FIG. 11 shows a simplified form of bandage 92 in which a gauze pad
94 is secured by a layer 96 of spun-bonded fabric to the surface of
skin 98, which skin may be the skin of a human or an animal. The
gauze pad 94 serves to absorb exudate from a wound 100 in the skin
98 and to protect the wound 100 from an external environment. The
gauze pad 94 is permeable to both water vapor and to air. The layer
96 is secured by an adhesive 102 to the surface of the skin 98, the
adhesive 102 being disposed along the bottom surface of the layer
94. The adhesive 102 also serves to secure the pad 94 to the layer
96. The spun-bonded fabric of the layer 96 is elastomeric with
three dimensional stretch, there being recoverable stretch in
excess of 100% along each of the three dimensions. Open regions of
the spun-bonded fabric occupy at least 30% of the total surface
area of the layer 96. Thickness of the layer 96 is in the range of
0.05 to 0.75 millimeters. These characteristics of the spun-bonded
fabric give the layer 96 the capacity to conform to undulations of
the skin 98, including a stretching of the skin in the situation
wherein the skin covers a limb which is being bent such as at a
knee or elbow. In addition, the open spaces or voids within the
fabric provides sufficient air permeability for increased comfort
to the person wearing the bandage. Since the bandage 92 does not
include the film 24 of FIG. 2, the bandage 92 of FIG. 11 is to be
employed only in those situations, such as mild skin irritations
and/or mild wounds in which external moisture is not a hazard, and
wherein the amount of exudate from the wound 100 is sufficiently
small so as to be totally absorbed by the pad 94.
It is to be understood that the above described embodiments of the
invention are illustrative only, and that modifications thereof may
occur to those skilled in the art. Accordingly, this invention is
not to be regarded as limited to the embodiments disclosed herein,
but is to be limited only as defined by the appended claims.
* * * * *